TEMPO-Mediated Electrochemical α-Allylation of Tetrahydroisoquinolines

A C(sp3)-H allylation of tetrahydroisoquinolines has been developed by combining Shono oxidation with a vinylogous Mannich-type reaction. TEMPO was used as the electrocatalyst to lower the electrode potential, improving functional group compatibility. This method provided a practical and efficient tandem procedure for the α-allylation of tetrahydroisoquinolines. The reaction proceeded through the formation of an iminium cation intermediate, which was generated in situ by anodic oxidation, followed by nucleophilic addition of 2-allylazaarenes.